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Common Rail Diesel Injection Systems

Common rail systems are now the preferred fuel injection technology for modern diesel engines. They provide significant benefits over older mechanical and hydraulic systems, including higher power and efficiency along with lower emissions. A common rail system uses a high pressure fuel pump to maintain very high pressure, over 30,000 psi, in common rail lines that feed each fuel injector. This allows precise electronic control of injection timing and quantity for optimal combustion. The high rail pressures enable improved atomization of fuel compared to older systems, enhancing performance and reducing emissions.

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389 views2 pages

Common Rail Diesel Injection Systems

Common rail systems are now the preferred fuel injection technology for modern diesel engines. They provide significant benefits over older mechanical and hydraulic systems, including higher power and efficiency along with lower emissions. A common rail system uses a high pressure fuel pump to maintain very high pressure, over 30,000 psi, in common rail lines that feed each fuel injector. This allows precise electronic control of injection timing and quantity for optimal combustion. The high rail pressures enable improved atomization of fuel compared to older systems, enhancing performance and reducing emissions.

Uploaded by

faris khairuddin
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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INTRODUCTION

Common Rail Systems are the future of diesel fuel injection


technology in both commercial and passenger vehicles. While this
technology first appeared in buses and trucks, it has been quickly
adapted for passenger vehicles to share the benefits across as
many applications as possible. These benefits include significant
increases in power and improved performance whilst drastically
reducing exhaust emissions, engine operating noise levels and
fuel consumption.

FUNCTIONS
The high pressure common rail is the injection type of choice for modern
diesel engines, far surpassing the capabilities of mechanical and hydraulic
injection systems of years past. Due to relatively high injection pressures
and greater control over injector events, common rail injection systems
feature favorable performance characteristics and lower emissions.
High pressure common rail injection systems, or simply common rails, are
the injection type of choice for modern diesel engines. The configuration's
superior performance characteristics and relatively high injection pressures
reduce emissions while improving efficiency. A common rail system is
comprised of a low pressure fuel pump (lift pump), high pressure fuel pump
(injection pump), Piezo electric fuel injectors, and the associated rail
system.

Fuel is delivered from the fuel tank to the injection pump via the lift pump.
The lift pump's only purpose is to consistently provide fuel to the injection
pump - the pressure of the fuel as it enters the injection pump is small and
has no effect on the actual pressure leaving an injector nozzle. The high
pressure pump maintains tremendous pressure within the common rail(s);
an I-6 engine features a single common rail that feeds each injector, while
a "V" engine will utilize two common rails, one for each engine bank. The
"rail pressure", or pressure of the fuel system at the outlet of the high
pressure pump, can reach pressures in excess of 30,000 psi.

Injection events are commanded by the PCM/ECM, which energizes an


injector in order to initiate an injection event. When this occurs, fuel flows
through the injector nozzle where it atomizes as it enters the combustion
chamber. The most important factor in a common rail system is rail
pressure; greater rail pressure yields greater atomization of fuel and is
therefore closely related with combustion efficiency.

The common rail system is an alternative to mechanical injectors and HEUI


systems, both of which lack the inherent ability to realize relatively high
injection pressures AND the ability to fire an injector multiple times per
single combustion event. This translates into greater performance potential,
lower particulate emissions, and greater efficiency. Common rail injection
types also typically reduce engine noise.

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